A known dynamic sense amplifier for a semiconductor memory device is designed to detect the slight difference between the potentials at a bit line and the associated dummy bit line from the amplified difference between the potentials at suitable sense nodes respectively associated with but isolated in effect from the particular bit line and associated dummy bit line. The sense nodes being thus not directly connected to the bit line and dummy bit line, the memory device will seldom err in reading the information represented by the potentials at the bit line and dummy bit line as would otherwise be caused due to, for example, a difference in stray capacitance between the lines. A semiconductor memory device is required to retain its output signal for a certain period of time during each readout cycle of the device to permit external units to operate properly in response to the information output from the memory device. The difference produced between the potentials at the sense nodes during each readout cycle of the device must be maintained throughout this period of time at a level correctly indicating the information read from the selected memory cell. It is for this reason required to have the sense amplifier of the memory device maintained active throughout such a period of time. This results in dissipation of a large amount of power and accordingly in generation of a large amount of heat during each cycle of operation of the device.
It is accordingly a prime object of the present invention to provide a semiconductor memory having an improved sense amplifier which may be maintained active for a reduced period of time during each readout cycle of the device.
The present invention contemplates resolution of such a problem through provision of an improved semiconductor memory device featuring, inter alia, a sense amplifier which may be maintained active for a significantly reduced period of time during each readout cycle of the device.